Chemistry:2011:CBSE:[All India]:Set-II
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Q1
What is meant by ‘lanthanoid contraction’?
Marks:1View AnswerAnswer:
There is a gradual decrease in atomic and ionic radii of lanthanoids (from lanthanum to lutetium) with an increase in atomic number. This is known as ‘lanthanoid contraction’.
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Q2
Draw the structure of 4-chloropentan-2-one.
Marks:1View AnswerAnswer:
The structure of 4-chloropentan-2-one is as follows:
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Q3
Define order of a reaction.
Marks:1View AnswerAnswer:
Order of a reaction is the sum of the exponents to which the concentration terms are raised in the rate law expression.
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Q4
Rearrange the following in an increasing order of their basic strengths:
C6H5NH2, C6H5N(CH3)2 (C6H5)2NH and CH3NH2Marks:1View AnswerAnswer:
(C6H5)2NH < C6H5NH2 < C6H5N(CH3)2 < CH3NH2
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Q5
What are lyophobic colloids? Give one example for them.
Marks:1View AnswerAnswer:
The colloidal systems in which the particles of dispersed phase have no or very little affinity for the dispersion medium are called lyophobic colloids.
Example: sols of silica, silver iodide, metal sulphides.
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Q6
Why is it that only sulphide ores are concentrated by ‘froath floatation process’?
Marks:1View AnswerAnswer:
Only sulphide ores are concentrated by froth floatation process because the surface of sulphide ores is preferentially wetted by oils while that of gangue is preferentially wetted by water.
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Q7
Write the IUPAC name of the following compound:
Marks:1View AnswerAnswer:
3-Bromo-2-methyl-propene
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Q8
Draw the structure of 2,6-Dimethylphenol.
Marks:1View AnswerAnswer:
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Q9
Calculate the packing efficiency of a metal crystal for a simple cubic lattice.
Marks:2View AnswerAnswer:
In a simple cubic lattice, the particles are located only at the corners of the cube and touch each other along the edge.
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Q10
The thermal decomposition of HCOOH is a first order reaction with a rate constant of 2.4 × 10–3 s–1 at a certain temperature. Calculate how long will it take for three-fourths of initial quantity of HCO2H to decompose. (log 0.25 = – 0.6021)
Marks:2View AnswerAnswer:
